scholarly journals Quantitative Analysis of Nuclear Lamins Imaged by Super-Resolution Light Microscopy

Cells ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 361 ◽  
Author(s):  
Mark Kittisopikul ◽  
Laura Virtanen ◽  
Pekka Taimen ◽  
Robert D. Goldman

The nuclear lamina consists of a dense fibrous meshwork of nuclear lamins, Type V intermediate filaments, and is ~14 nm thick according to recent cryo-electron tomography studies. Recent advances in light microscopy have extended the resolution to a scale allowing for the fine structure of the lamina to be imaged in the context of the whole nucleus. We review quantitative approaches to analyze the imaging data of the nuclear lamina as acquired by structured illumination microscopy (SIM) and single molecule localization microscopy (SMLM), as well as the requisite cell preparation techniques. In particular, we discuss the application of steerable filters and graph-based methods to segment the structure of the four mammalian lamin isoforms (A, C, B1, and B2) and extract quantitative information.

2020 ◽  
Vol 2 (1) ◽  
pp. 323-331 ◽  
Author(s):  
Pia Otto ◽  
Stephan Bergmann ◽  
Alice Sandmeyer ◽  
Maxim Dirksen ◽  
Oliver Wrede ◽  
...  

We investigate the internal structure of smart core–shell microgels by super-resolution fluorescence microscopy by combining of 3D single molecule localization and structured illumination microscopy using freely diffusing fluorescent dyes.


2015 ◽  
Vol 26 (22) ◽  
pp. 4075-4086 ◽  
Author(s):  
Takeshi Shimi ◽  
Mark Kittisopikul ◽  
Joseph Tran ◽  
Anne E. Goldman ◽  
Stephen A. Adam ◽  
...  

The nuclear lamina is a key structural element of the metazoan nucleus. However, the structural organization of the major proteins composing the lamina is poorly defined. Using three-dimensional structured illumination microscopy and computational image analysis, we characterized the supramolecular structures of lamin A, C, B1, and B2 in mouse embryo fibroblast nuclei. Each isoform forms a distinct fiber meshwork, with comparable physical characteristics with respect to mesh edge length, mesh face area and shape, and edge connectivity to form faces. Some differences were found in face areas among isoforms due to variation in the edge lengths and number of edges per face, suggesting that each meshwork has somewhat unique assembly characteristics. In fibroblasts null for the expression of either lamins A/C or lamin B1, the remaining lamin meshworks are altered compared with the lamin meshworks in wild-type nuclei or nuclei lacking lamin B2. Nuclei lacking LA/C exhibit slightly enlarged meshwork faces and some shape changes, whereas LB1-deficient nuclei exhibit primarily a substantial increase in face area. These studies demonstrate that individual lamin isoforms assemble into complex networks within the nuclear lamina and that A- and B-type lamins have distinct roles in maintaining the organization of the nuclear lamina.


2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Tatjana Trcek ◽  
Markus Grosch ◽  
Andrew York ◽  
Hari Shroff ◽  
Timothée Lionnet ◽  
...  

Abstract Germ granules, specialized ribonucleoprotein particles, are a hallmark of all germ cells. In Drosophila, an estimated 200 mRNAs are enriched in the germ plasm, and some of these have important, often conserved roles in germ cell formation, specification, survival and migration. How mRNAs are spatially distributed within a germ granule and whether their position defines functional properties is unclear. Here we show, using single-molecule FISH and structured illumination microscopy, a super-resolution approach, that mRNAs are spatially organized within the granule whereas core germ plasm proteins are distributed evenly throughout the granule. Multiple copies of single mRNAs organize into ‘homotypic clusters’ that occupy defined positions within the center or periphery of the granule. This organization, which is maintained during embryogenesis and independent of the translational or degradation activity of mRNAs, reveals new regulatory mechanisms for germ plasm mRNAs that may be applicable to other mRNA granules.


Author(s):  
Kirti Prakash

We report that high-density single-molecule super-resolution microscopy can be achieved with a conventional epifluorescence microscope set-up and a mercury arc lamp. The configuration termed as laser-free super-resolution microscopy (LFSM) is an extension of single-molecule localization microscopy (SMLM) techniques and allows single molecules to be switched on and off (a phenomenon termed as ‘blinking’), detected and localized. The use of a short burst of deep blue excitation (350–380 nm) can be further used to reactivate the blinking, once the blinking process has slowed or stopped. A resolution of 90 nm is achieved on test specimens (mouse and amphibian meiotic chromosomes). Finally, we demonstrate that stimulated emission depletion and LFSM can be performed on the same biological sample using a simple commercial mounting medium. It is hoped that this type of correlative imaging will provide a basis for a further enhanced resolution. This article is part of the Theo Murphy meeting issue ‘Super-resolution structured illumination microscopy (part 1)’.


2020 ◽  
Author(s):  
Murat Sunbul ◽  
Jens Lackner ◽  
Annabell Martin ◽  
Daniel Englert ◽  
Benjamin Hacene ◽  
...  

AbstractRhoBAST is a novel fluorescence light-up RNA aptamer (FLAP) that transiently binds a fluorogenic rhodamine dye. Fast dye association and dissociation result in intermittent fluorescence emission, facilitating single-molecule localization microscopy (SMLM) with an image resolution not limited by photobleaching. We demonstrate RhoBAST's excellent properties as a RNA marker by resolving subcellular and subnuclear structures of RNA in live and fixed cells by SMLM and structured illumination microscopy (SIM).


2020 ◽  
Vol 21 (3) ◽  
pp. 744 ◽  
Author(s):  
Hannes Gonschior ◽  
Volker Haucke ◽  
Martin Lehmann

The tight junction (TJ) and the adherens junction (AJ) bridge the paracellular cleft of epithelial and endothelial cells. In addition to their role as protective barriers against bacteria and their toxins they maintain ion homeostasis, cell polarity, and mechano-sensing. Their functional loss leads to pathological changes such as tissue inflammation, ion imbalance, and cancer. To better understand the consequences of such malfunctions, the junctional nanoarchitecture is of great importance since it remains so far largely unresolved, mainly because of major difficulties in dynamically imaging these structures at sufficient resolution and with molecular precision. The rapid development of super-resolution imaging techniques ranging from structured illumination microscopy (SIM), stimulated emission depletion (STED) microscopy, and single molecule localization microscopy (SMLM) has now enabled molecular imaging of biological specimens from cells to tissues with nanometer resolution. Here we summarize these techniques and their application to the dissection of the nanoscale molecular architecture of TJs and AJs. We propose that super-resolution imaging together with advances in genome engineering and functional analyses approaches will create a leap in our understanding of the composition, assembly, and function of TJs and AJs at the nanoscale and, thereby, enable a mechanistic understanding of their dysfunction in disease.


Author(s):  
Lucia C. S. Wunderlich ◽  
Florian Ströhl ◽  
Stefan Ströhl ◽  
Oliver Vanderpoorten ◽  
Luca Mascheroni ◽  
...  

AbstractImmunofluorescence microscopy is routinely used in the diagnosis of and research on renal impairments. However, this highly specific technique is restricted in its maximum resolution to about 250 nm in the lateral and 700 nm in the axial directions and thus not sufficient to investigate the fine subcellular structure of the kidney’s glomerular filtration barrier. In contrast, electron microscopy offers high resolution, but this comes at the cost of poor preservation of immunogenic epitopes and antibody penetration alongside a low throughput. Many of these drawbacks were overcome with the advent of super-resolution microscopy methods. So far, four different super-resolution approaches have been used to study the kidney: single-molecule localization microscopy (SMLM), stimulated emission depletion (STED) microscopy, structured illumination microscopy (SIM), and expansion microscopy (ExM), however, using different preservation methods and widely varying labelling strategies. In this work, all four methods were applied and critically compared on kidney slices obtained from samples treated with the most commonly used preservation technique: fixation by formalin and embedding in paraffin (FFPE). Strengths and weaknesses, as well as the practicalities of each method, are discussed to enable users of super-resolution microscopy in renal research make an informed decision on the best choice of technique. The methods discussed enable the efficient investigation of biopsies stored in kidney banks around the world.


Author(s):  
Rainer Heintzmann

This article presents answers to the questions on superresolution and structured illumination microscopy (SIM) as raised in the editorial of this collection of articles ( https://doi.org/10.1098/rsta.2020.0143 ). These answers are based on my personal views on superresolution in light microscopy, supported by reasoning. Discussed are the definition of superresolution, Abbe's resolution limit and the classification of superresolution methods into nonlinear-, prior knowledge- and near-field-based superresolution. A further focus is put on the capabilities and technical aspects of present and future SIM methods. This article is part of the Theo Murphy meeting issue ‘Super-resolution structured illumination microscopy (part 1)’.


2019 ◽  
Author(s):  
Fabian U. Zwettler ◽  
Marie-Christin Spindler ◽  
Sebastian Reinhard ◽  
Teresa Klein ◽  
Andreas Kurz ◽  
...  

AbstractThe synaptonemal complex (SC) is a meiosis-specific nuclear multiprotein complex that is essential for proper synapsis, recombination and segregation of homologous chromosomes. We combined structured illumination microscopy (SIM) with different ExM protocols including U-ExM, proExM, and magnified analysis of the proteome (MAP) to investigate the molecular organization of the SC. Comparison with structural data obtained by single-molecule localization microscopy of unexpanded SCs allowed us to investigate ultrastructure preservation of expanded SCs. For image analysis, we developed an automatic image processing software that enabled unbiased expansion factor determination. Here, MAP-SIM provided the best results and enabled reliable three-color super-resolution microscopy of the SCs of a whole set of chromosomes in a spermatocyte with 20-30 nm spatial resolution. Our data demonstrate that post-expansion labeling by MAP-SIM improves immunolabeling efficiency and allowed us thus to unravel previously hidden details of the molecular organization of SCs.


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